Liquid-fuel vaporization



Dec. 14, 1926.

1,610,653 R. E. BREWER LIQUID FUEL VAPORIZATI ON Filed June 16. 1921 Y I ii /7 -HE P J1; w J a ,9 a

amrm Patented. Dec. I 14, 1926.

UNITED STATES P NT- OFFIGE.

ROBERT BREWER. F BOSTON .-MASSACHUSETTS, *ASSIGNOR T0 BUTLER .A'MES, or

LOWELL, MASSACHUSETTS.

LIQUID FUEL VAPORIZATION.

Application filed .Tune 16, 1921. Serial No. 4878,07 1;

tion which preserves a predetermined proportion between air and fuel, affected but little if at all by variations in external 'con-' ditions such as atmospheric pressure, and which is conditioned primarily on transforming the fuel into its gaseous condition before it is subjected to the regulative opera tion of the fuel gas measuring factors of the carbureter.

When both ingredients destined to pro du e the combustible mixture are in the condition of gas, the same laws of flow through orifices and ducts apply to both, and gas flow factors may be so applied-according to my invention, that predetermined weights of gaseous fuel and of air, passing per unit of time into the duct or chamber where they mingle. are regulated,-with substantial accuracy. and the proportion of the two ingredients held under control.

'-All carburetors which function by delivering fuel in the liquidalbeit finely divided condition to the moving column of air in which eventually the fuel is to be vaporized labor under the disadvantage due to the relatively great density of the fuel in its liquid condition. Regulation of the weight of the fuel gas ultimately produced, by initial regulation of the delivery of the same fuel in liquid form, is impossible to achieve with any approach to accuracy or delicacy, since the minutest globule ofv the liquid fuel expands enormously in passing to the gaseous state. Many carbureters have been designed with provisions for converting liquid fuel into gas before its mixture with the column, butnone, so far as I am informed, which utilize the vapor pressure, incidental to the conversion, to regulate automatically the weight of liquid fuel inducted into the vaporizer, and at the same time automatically regulate the flow of'fuel gas from the vaporizer to the air column. The manner in which these regulatively coacting factors operate is characteristic of my invention, and will be further explained in association with the description of a carbureter of which the drawings hereto annexedare illustrative.

In'these drawings, Fig. 1 is a verticalsection showing allthe essential parts of the carbureter:

Fig. 2 is a horizontal section, taken at the I line 2-2 of Fig. 1;

lziig. 3 is a section on line 3-3 of Fig. 4; an

Fig. 4 is a view in elevation, much enlarged, ofa part of the liquid fuel induct,

B represents a receptacle for vaporizable liquid fuel, which may be of the spontaneously vaporizing type, such as gasoline, or a heavier and less volatile liquid fuel. As illustrated, this receptacle is shown as of the float-valve variety, containing a float 2, but

its specific character is immaterial.

P is a tube, open to the atmosphere at one end, and terminating inside a second tube P; these two forming a continuous duct from the atmosphere to the vaporizer G. The vaporizer may have longitudinal ribs 6 on the inside and circumferential ribs 7 on the outside as shown in Fig. 1, At p the tube P is constricted so as to form a venturi, and at L is perforated or slotted, to provide an inlet for liquid fuel, The perforation L is located at or near the minimum pressure in the venturi p. The tube P and the portion of tube P above inlet L constitute a liquid-fuel duct leading to the vaporizer G.

To provide means for raising liquid fuel from the supply in the receptacle B, a tu bular skirt 5 surrounds the housing 1 of the tube P; this housing is apertured at 4 to give access to the perforation L. It should be noted that the opening 3 which may be used to introduce highly volatile fuel when it is necessary to prime the vaporizing carbureter, 1s normally closed.

It will be understood, that when a fall in pressure in the vaporizer G produces air flow from the outer atmosphere through the duct P, P, the low pressure supervening at the throat of the venturi 7) will cause the liquid fuel to rise inside the skirt 5 and enter the tube .P :at L. The rapidly moving air column in the tube P acts as an aspirator which draws the liquid fuel from within the skirt 5, breaking the liquid fuel. into'small hlobules, and carries it into the vaporizer G. This air column in the tubes P, P, functions essentially, as a vehicle to convey fuel in liquid form to the vaporizer. While point of.

the air thus inducted into the vaporizer with the liquid fuel to. some'extent modifies the constitution of the gas or vapor. therein maintenance of fuel in gaseous form, with substantially Ilqfill 1n mixture, as a reset V011 from WhlC to draw fuel gas into a moving" air column, so that the flow of both air and fuel are independently regulated as gases, and their proportions thus controlled. The pressuredifferential responsible for fall in pressure in'the vaporizer Gr below that" of the atmosphere is produced bythe operationof the venturi V, formed in the main air column tube or air duct D, which by continuation becomes the mixing tube or combustible mixture duct M, leading to the. engine or generically equivalent apparatus supplied by the carbureter." The inlet end A Y of this air tube contains the regulating and constricting valves T and C, presently to bev i at constant speed. The minimum pressure at the throat of the venturi V determines the described.

A branch duct F which enters the venturi, V at or near its point of minimum static pressure, connects the vaporizer'G with the main air duct. The effective cross-section of this branch duct F is determined by the position of the rotatable plate-valve R, which is secured to the end of tube P as to a stem. The tube P is mounted to rotate on its axis: an externally accessible crank T, secured to the tube P, supplies means for rotatably changing the position of the tube P" and with it the plate-valve R. Thus the crank T and its operating connections constitute means for conjointly controlling the air valve or regulator T and the vapor valve R. The orifice R in the plate valve R is tapered in form as shown in Fig.- 2, so that the effective cross-sectional area of the branch duct F may be varied.

Attention is now drawn to the fact that the minimum pressure determinant at the neck of the venturi V is the factor operating alike to induce air flow from the atmosphere through the inlet A, and gas flow from the vaporizer G. lVhile the pressure in the vaporizer G'is lower than that of the atmosphere, the differential will not be very great while the demand on the carbureter remains constant.

The liquid fuel inducted into the vaporizer G is there converted into gas by the application of heat. complished in the manner usual with liquid fuel Vaporizers employed with internal combustion engines, that is by placing the vapor izer inside a chamber H, which is connected with, or forms part of, the exhaust pipe of the engine.

While I do not regard it as essential, it has nevertheless been found desirable to provide for variations in the size of the liquid fuel inlet L, to keep pace, roughly, with variations in the freedom of air passage in the inand ie' I 1 On the outside of the tube P, in the air inlet A, there is secured the air supply regulating valve T. The independent choke valve C, also in the air inlet A,'may be used toproduce. special regulation of air supply, and ordinarily will not be moved fromthe setting which has been-determined on as .tubel is rotated, uncovers more or less of the aperture L. This is illustrated in Figs.

proper for the particular fuel used, or thegeneral' atmospheric condition.

The operation of the carbureter, above structurally described, is as follows: Assume the valves 77,, T, and R t'o be at their positions of widest opening (as shown in Fig. l) andithe engine running under full load and pressure differentials which lrespectively cause airflow into the inlet A and gas flow into-the branch duct F. The flow of air, with its burden of liquid fuel, through the duct P, P:, is determined by the pressure differential between the interior of the va porizer G and the atmosphere. The liquid fuel, vaporized by the heat applied to the vaporizer G, produces 'or assumes a vapor pressure, which operates as a back pressure, or rather reduces the value of the pressure differential as between the interior of the vaporizer and thej atmosphere, below the value represented by the pressure differential asbetween the venturi V and thev atmosphere The' effect is to produce a condition of balancabetwe'en demand and supply, and thusto' maintain a substantially constant pressure in the vaproportionof these ingredients will be con- This may be conveniently acstant.

The automatic regulation of liquid fuel flow into the apparatus will perhaps be more clearly understood-by a. description ofthe behavior of a carbureter possessing such functionally related factors as are above described, when the engine which it feeds is being started, mean partsare cold.

. and through the duct 1 P is, substantially,

that between the pressure at the venturi V and theatmosphere. The small size of the duct I, P produces a rapid flow of air through it, and the static pressure at the throat of the venturi 7) falls to acorrespondingly low value, inducing. a copious flow of liquid fuel through the aperture L. If the engine is to be run on a relativelyheavy and slowly volatile fuelleventually, a highly volatile fuel should be supplied at starting,

through the priming passage 3. The engine will be supplied, at, the start. with a rich mixture of fuel and air. which is precisely as it should be. I

Then the engine starts, and before the exhaust gases have heated the vaporizer G, the supply of rich mixture goes directly'to the engine; the conditions being there much through the aperture L.

as when the usual tvpe of gasoline carbureters isemployed. Presently, however, the vaporizer G becomes hot. the liquid fuel entering it is vaporized, and exerts its vapor pressure, producing a reduced pressureditferential as between the interior of the vaporizer and the outer atmosphere; this reduction in pressure differential reduces the speed of the air column in the duct P. P, and therefore the indraft of liquid fuel This repression of the air column which serves as the vehicle for liquid fuel progresses uptil a balance has i been automatically reached.

(ill

Variations in condition, as by variation of position of the valves 7). T and'R, are responded to be similar self-adjustment of pressure-(1iflerentials in the apparatus. If the external atmospheric pressure varies, as when the altitude of the apparatus is changed, the differential relationships in the carbureter do not alter in proportion to the barometric change, but on the contrary remain substantially the same, unless the altitude changes he verygreat, as is often the case in an ascending or descendingairplane.

With the liquid fuel introduced into the small air duct P. as above described, the

liquid fuel is sprayed into the vaporizer with considerable velocity and is distributed throue'hout the vaporizer. thereby subjectins all the. fuel to approximately the same temperature and at the same time drawing heat uniformly from the entire area of the reter, a combustible-mixture duet. an air duct, leading thereto from the outer atmosphere; a substantially closed vaporizing chamber, separate from the combustible n'lixture duct. a vapor duct leading from said chamber into the air duct, an air and fuel duct independent of said air duct, leadinginto the chamber from the outer atmosphere and adapted to carry a stream of air therethrough, and means for admitting fuel into the air stream in said air andfuel duct and spraying the same into said vaporizing chamber.

2. In a combined oil vaporizer and carburetor, a combustible-mixture duct,-an air an air column moving therethrough, a

closed vaporizing chamber, separate from the combustible mixture duct. a vapor duct leading from the chamber into the air duct at its constriction, an air and fuel duct, independent of said air duct, leading into the chamber, and adapted to conduct a stream of air therethrough, and means for aspirating, and spraying fuel through. said air and fuel ductinto said. vaporizing, chamber.

3. In a combined oil vaporizer and carbureter, a combustible-mixture duct, an air duct leading thereto from the outer atmosphere. a closed vaporizing chamber, separate from the combustible-mixture duct, a vapor duct leading from the chamber into the air duct and con'iprisint, an aspiratine' vapor-orifice an air and fuel duct independen; of said air duct, leading intothe cham-.

bureter, a combustibleunixture duct, an air duct leading thereto from the outer atmosphere and provided with a constriction adapted locally to reduce static pressure in an air column moving, therethrough, a closed vaporizing chamber, separate from the combustiblemixture duct, a vaporduct leading from the chamber into the main air duct at its constriction, comprising an aspirat-ing vapororifice and means for controlling the flow of vapor therethrongh, an air andifuel duct independent of said air duct, leading into the chamber from the outer atmosphere and adapted to conduct a stream of air therethrough. and means for introducing fuel into said air stream. i

In a combined oil vaporizer and carbureter, a combustible-mixture duct, a main air 'duct leading thereto from the outer atmosphere and provided with a constriction adapted locally to reduce static pressure in an air column moving therethrough, a substantially closed vaporizing chamber, separate from the combustible-mixture duct, a

'vapoi 'duct leading from the chamber into the aird'uct-at its constricted region, an air and fuel duct, inde endent of said air duct, leading. intothe c amber from the outer atmosphere and adapted to conduct a stream of air therethrough, means for introducing fuel; into said air stream, means for controllingathe How of vapor through said vapor duct, and means in said air duct to vary its eifectivecross-section.

61111; a combined oil ,vaporizer and carbureter, a combustible-mixture duct and an air" duct leading thereto from the outer atmosphere, a substantially closed vaporizing chamber, separate from the combustiblemixture duct, a vapor-duct leadin from the vaporizing chamber into the air duct, an air and fuel duct independent of said air duct, leading into said chamber from the outer atmosphere, means between the chamber and the outer atmosphere in said air and fuel duct to introduce liquid fuel into said chamher, and means to vary proportionately the effective cross-section of said air duct and of said vapor duct.

7. In a combined oil vaporizer and carburetor, a combustible-mixtureduct, an air duct leading thereto from the outer atmosphere and provided with a constriction adapted locally to reducestatic pressure in an air column moving therethrou 'h,-a substantially closed vaporizing chain er, separate from said combustible-mixture duct, a vapor duct leading from the vaporizing chamber into the main air duct at its constricted region, an air and fuel duct independent of said air duct, leading into said chamber from the outer atmosphere and adapted to conduct a stream of air therethe main air duct at its constricted region,

a -elatively-fsmall air and fuel duct, independentlolifsaid main air duct, leading into said chamberfrom the outer atmosphere and adapted to conduct a stream of air therethrough and thereby to aspirate liquid fuel into the chamber, and means to vary the effe tiye cross-section of said air duct, said air "and fuel duct, and of the vapor duct.

9. In a combined oil vaporizer and carbureter, a combustible-mixture duct, a main air duct leading thereto from. the outer atmosphere, a,subst a-ntially closed vaporizing chamber, a vapor duct leading from the chamber into the main air duct, an air and fuel duct leading to said chamber from the outer atmosphere and adapted to conduct a stream of air therethrough, aspirating means for spraying liquid fuel into said air stream and thence to said chamber, and means for conjointly controlling the fuel supply and flow of air and vapor through said air and fuel duct and vapor duct, respectively, with .respect to the air stream in the main air duct.

Signed by me at Boston, Massachusetts, this 19th day bf May, 1921. ROBERT E. BEEVVER. 

